1. Field of the Invention
The present invention relates to a dust removing machanism in an open-end spinning frame. More particularly, the invention relates to an improvement in the dust removing mechanism of the type where dust is caused by a centrifugal action to be removed through a dust removing opening formed on a casing of an opening roller while fibers are being opened and delivered by the opening roller.
2. Description of the Prior Art
When impurities and foreign matter such as dust, neps, leaf pieces, seed pieces and chemical adhering substances (inclusively referred to as "dust" hereinafter) are contained in material fibers, there is a tendency to collect the dust in a twisting zone and the spinning operation for forming yarn from the fibers becomes unstable, resulting in a reduction of the yarn quality.
Accordingly, the method, in which a dust removing opening is formed at a part of a fiber-opening zone, wherein an opening roller is disposed upstream of the twisting zone, and dust is caused to fly off through this dust removing opening by a centrifugal force, has been adopted in various modes. However, satisfactory results can not be obtained according to this known method.
Since the dust removal from the dust removing opening depends on centrifugal force thereof, fibers also are caused to fly off by the centrifugal force thereof. As means for preventing the flying-off of fibers, there has been proposed a method in which an auxiliary air stream is applied to flow toward the dust removing opening so that the stream is introduced into the opening. In this method, dust having a large mass is allowed to fly off from the dust-separating zone against the carrying force of this auxiliary air stream, but fibers having a smaller mass are caught by this air stream and are not allowed to fly off from the above-mentioned zone, and are delivered to the twisting zone by the opening roller. In this method, the dust-removing effect is remarkably influenced by the intensity of the auxiliary air stream and the direction of flow thereof, and therefore, delicate adjustment of the air stream is required at the dust-removing opening.
Further, there has been proposed a method in which, in order promptly to discharge dust flying off from the dust-separating zone which is connected to the dust-removing opening while preventing this dust from staying in the vicinity of the dust-removing opening, a sucking air stream flowing in a dust-discharging zone adjacent to the dust-separating zone is introduced into the dust-separating zone. In this method, adjustment of the relation between the discharge sucking air stream and the auxiliary air stream in the separating zone is very complex and difficult. More specifically, in order to promptly discharge dust flying off from the dust-removing opening and separating zone, it is necessary to produce the above-mentioned discharge sucking air stream at a position close to the separating zone and it is also necessary to increase the intensity of this sucking air stream. However, if the intensity of the sucking air stream is enhanced, the sucking air stream influences the separating zone and disturbs the smooth flowing of the auxiliary air stream, and also, causes fibers to be discharged. If the intensity of the sucking air stream is reduced to prevent fiber loss, the influence in the separating zone is lost causing adhesion and deposition of dust and fine fibers to the walls of the separating zone and dust-discharging zone. When dust stays on the walls, leaf pieces and the like act as nuclei and fine fibers adhere to and gather around these nuclei, and dust is gradually accumulated on the walls. When the degree of accumulation of dust on the walls exceeds a certain limit, it is scattered in the form of large masses by the action of the air streams and these dust masses are influenced by the auxiliary air stream directed toward the dust removing opening. As a result, these dust masses are sucked into the dust removing opening. This phenomenon occurs when adjustment of the air streams is not appropriately carried out.